Sex ratio and mate preferences: a cross‐cultural investigation

Sex ratio is the number of men per 100 reproductive‐age women within a specified mating pool. We generated and tested two hypotheses about the cross‐cultural relationships between sex ratio and mate preferences using preference ratings of 18 characteristics provided by 9809 participants and corresponding sex ratio data secured from an international organization. The Classical Sex Ratio Mate Preference Shifts Hypothesis predicts that in imbalanced sex ratio societies, the more numerous sex will lower their standards, to facilitate acquisition of a partner of the less numerous sex. The Alternative Sex Ratio Mate Preference Shifts Hypothesis predicts that in lower sex ratio societies, men will lower their standards to secure more short‐term matings, whereas women will raise their standards to avoid deception by men seeking short‐term relationships. Results supported the Classical Sex Ratio Mate Preference Shifts Hypothesis for men, and the Alternative Sex Ratio Mate Preference Shifts Hypothesis for women. Discussion addresses limitations of the current research and highlights future directions for research on the relationships between sex ratio and mating psychology and behavior. Copyright © 2006 John Wiley & Sons, Ltd.     

The role of visuospatial and verbal working memory in perceptual category learning

The role of verbal and visuospatial working memory in rule-based and information-integration category learning was examined. Previously, Maddox, Ashby, Ing, and Pickering found that a sequentially presented verbal working memory task did not affect information-integration learning, but disrupted rule-based learning when the rule was on the spatial frequency of a Gabor stimulus. This pattern was replicated in Experiment 1, in which the same category structures were used, but in which the verbal working memory task was replaced with a visuospatial analog. Experiment 2A examined rule-based learning on an oblique orientation and also found both verbal and visuospatial working memory tasks disrupting learning. Experiment 2B examined rule-based learning on a cardinal orientation and found a minimal effect of the verbal working memory task, but a large effect of the visuospatial working memory task. The conceptual significance of cardinal orientations and the role of visuospatial and verbal working memory in category learning are discussed.     

Genetic and environmental influences on the positive traits of the values in action classification,and biometric covariance with normal personality

Virtually all human individual differences have been shown to be moderately heritable. Much of this research, however, focuses on measures of dysfunctional behavior and relatively fewer studies have focused on positive traits. The values in action (VIA) project is a comprehensive and ambitious classification of 24 positive traits, also known as character strengths (Peterson, C., & Seligman, M. E. P. (2004). Character strengths and virtues: A handbook and classification. Washington, DC: American Psychological Association), the majority of which have received no behavior genetic attention. Using a sample of 336 middle-aged twins drawn from the Minnesota Twin Registry who completed the VIA inventory of strengths, we detected significant genetic and non-shared environmental effects for 21 of 24 character strengths with little evidence of shared environmental contributions. Associations with a previously administered measure of normal personality found moderate phenotypic overlap and that genetic influences on personality traits could account for most, but not all, of the heritable variance in character strengths.     

Methodological and dispositional predictors of congruence between implicit and explicit need for achievement

In this research, the authors questioned the statistical independence of implicit and explicit motives. Their first aim was to identify a methodological factor that may have weakened implicit-explicit motive correlations in past research. Their second aim was to identify personality traits that moderate implicit-explicit motive congruence. They found that implicit and explicit need for achievement (nAch) are significantly correlated, but only if the implicit and explicit measures are matched in content. Three traits were found to uniquely moderate the relationship between implicit and explicit nAch: private body consciousness, self-monitoring, and preference for consistency. These findings indicate that implicit and explicit nAch are systematically related and suggest that some individuals may use implicit nAch as a foundation for the development of explicit nAch.     

Parallel neural systems for classical conditioning: Support from computational modeling

Classical conditioning has been explained by two main types of theories that postulate different learning mechanisms. Rescorla and Wagner (1972) put forth a theory in which conditioning is based on the ability of the US to drive learning through error correction. Alternatively, Mackintosh (1973) put forth a theory in which the ability of the CS to be associated with the unconditioned stimulus is modulated. We have proposed a reconciliation of these two mechanisms as working in parallel within different neural systems: a cerebellar system for US modulation and a hippocampal system for CS modulation. We developed a computational model of cerebellar function in eyeblink conditioning based on the error correction mechanism of the Rescorla-Wagner rule in which learningrelated activity from the cerebellum inhibits the inferior olive, which is the US input pathway to the cerebellum (Gluck et al., 1994). We developed a computational model of the hippocampal region that forms altered representations of conditioned stimuli based on their behavioral outcomes (Gluck & Myers, 1993; Myers et al., 1995). Overall, computational modeling and empirical findings support the idea that, at least in the case of eyeblink conditioning, there may be two different neural systems: the cerebellum which mediates US-based error correction and hippocampus which alters representations of CSs.     

Use of current explanations in multicausal abductive reasoning

In multicausal abductive tasks a person must explain some findings by assembling a composite hypothesis that consists of one or more elementary hypotheses. If there are n elementary hypotheses, there can be up to 2ⁿ composite hypotheses. To constrain the search for hypotheses to explain a new observation, people sometimes use their current explanation—the previous evidence and their present composite hypothesis of that evidence; however, it is unclear when and how the current explanation is used. In addition, although a person's current explanation can narrow the search for a hypothesis, it can also blind the problem solver to alternative, possibly better, explanations. This paper describes a model of multicausal abductive reasoning that makes two predictions regarding the use of the current explanation. The first prediction is that the current explanation is not used to explain new evidence if there is a simple (i.e., nondisjunctive, concrete) hypothesis to account for that evidence. The second prediction is that the current explanation is used when attempting to discriminate among several alternative hypotheses for new evidence. These hypotheses were tested in three experiments. The results are consistent with the second prediction: the current explanation is used when discriminating among alternative hypotheses. However, the first prediction—that the current explanation is not used when a simple hypothesis can account for new data—received only limited support. Participants used the current explanation to constrain their interpretation of new data in 46.5% of all trials. This suggests that context-independent strategies compete with context-dependent ones—an interpretation that is consistent with recent work on strategy selection during problem solving.     

Evaluation of the psychometric properties of two forgiveness scales

This study examined the psychometric properties of two forgiveness scales using participants enrolled at a Midwestern Catholic university (N = 328). The Forgiveness Scale is a 15—item Likert-type scale designed to measure forgiveness toward an of-fender. The Forgiveness Likelihood Scale is a 10—item Likert-type scale designed to measure tendency to forgive across situations. Factor analyses revealed that the For-giveness Scale contains two subscales (i.e., Absence of Negative, Presence of Posi-tive) and the Forgiveness Likelihood Scale consists of a single factor. Both scales have adequate internal consistency and test-retest reliability. Both subscales of the Forgiveness Scale were significantly correlated in the expected direction with mea-sures of forgiveness, religiousness, anger, hope, religious well-being, existential well-being, and social desirability. The Forgiveness Likelihood Scale was significantly correlated in the expected direction with measures of forgiveness, religiousness, trait anger, religious well-being, and social desirability. The authors thank Sarah Danko, Anne Hovancsek, Carla Kmett, Jennifer Martin, and Colleen Ryan for their assistance. We kindly request that researchers who use the forgiveness scales evaluated in this study provide us with a summary of their psychometric data for the scales. The idea for creating the Forgiveness Likelihood Scale was based upon the Willingness to Forgive Scale (Hebl & Enright, 1993).     

Cerebellar Substrates for Error Correction in Motor Conditioning

The authors evaluate a mapping of Rescorla and Wagner's (1972) behavioral model of classical conditioning onto the cerebellar substrates for motor reflex learning and illustrate how the limitations of the Rescorla-Wagner model are just as useful as its successes for guiding the development of new psychobiological theories of learning. They postulate that the inhibitory pathway that returns conditioned response information from the cerebellar interpositus nucleus back to the inferior olive is the neural basis for the error correction learning proposed by Rescorla and Wagner (Gluck, Myers, & Thompson, 1994; Thompson, 1986). The authors' cerebellar model expects that behavioral processes described by the Rescorla-Wagner model will be localized within the cerebellum and related brain stem structures, whereas behavioral processes beyond the scope of the Rescorla-Wagner model will depend on extracerebellar structures such as the hippocampus and related cortical regions. Simulations presented here support both implications. Several novel implications of the authors' cerebellar error-correcting model are described including a recent empirical study by Kim, Krupa, and Thompson (1998), who verified that suppressing the putative error correction pathway should interfere with the Kamin (1969) blocking effect, a behavioral manifestation of error correction learning. The authors also discuss the model's implications for understanding the limits of cerebellar contributions to associative learning and how this informs our understanding of hippocampal function in conditioning. This leads to a more integrative view of the neural substrates of conditioning in which the authors' real-time circuit-level model of the cerebellum can be viewed as a generalization of the long-term memory module of Gluck and Myers' (1993) trial-level theory of cerebellar-hippocampal interaction in motor conditioning.     

Reduced right hemisphere activation in severely abused violent offenders during a working memory task: An fMRI study

This study uses functional magnetic resonance imaging (fMRI) to address two important gaps in our knowledge of brain functioning and violence: (1) What are the brain correlates of adults in the community who have suffered severe physical abuse early in life and who go on to perpetrate serious violence in adulthood? (2) What characterizes those who experience severe physical abuse but who refrain from serious violence? Four groups of participants recruited from the community (controls, severe physical child abuse only, serious violence only, and severely abused, seriously violent offenders) underwent fMRI while performing a visual/verbal working memory task. Violent offenders who had suffered severe child abuse show reduced right hemisphere functioning, particularly in the right temporal cortex. Abused individuals who refrain from serious violence showed relatively lower left, but higher right, activation of the superior temporal gyrus. Abused individuals, irrespective of violence status, showed reduced cortical activation during the working memory task, especially in the left hemisphere. Brain deficits were independent of IQ, history of head injury, task performance, cognitive strategy, and mental activity during the control task. Findings constitute the first fMRI study of brain dysfunction in violent offenders, and indicate that initial right hemisphere dysfunction, when combined with the effects of severe early physical abuse, predisposes to serious violence but that relatively good right hemisphere functioning protects against violence in physically abused children. Aggr. Behav. 27:111–129, 2001. © 2001 Wiley‐Liss, Inc.